The invention relates to improvements in method and apparatus for the filteration and handling of liquid materials to provide a clear sample for analysis or other testing. Particularly, it is directed to pressure differential filtering devices and methods characterized by an outer tube adapted to hold the liquid to be filtered and an inner tube having a filter head adapted to be inserted into the tube and to engender a pressure on the liquid therein to force it up through the filter head into the inner tube. In the apparatus and methods heretofore available, the inner tube containing the filtered liquid is withdrawn and the filtered liquid poured into a suitable test tube and transferred therein to a suitable testing apparatus. Methods and apparatus of this general kind are found in U.S. Pat. Nos. 3,661,265; 3,693,804; and 3,799,342.